From the invention of paper thousands of years ago to the present date, paper has been used as the preferred medium by individuals and societies for the recording, processing and storing of information. With the introduction of computers into society, many of the functions previously performed exclusively with paper are now being accomplished by writing information on paper and entering the written information into a computer. Typically, the information written on paper is entered into computers by optically scanning the paper. The foregoing method of entering information into computers is inconvenient, because the paper must be placed directly on the scanner, and no intervening objects may be placed between the paper and the scanner. Another method utilized by the prior art for writing information on paper and entering the written information into a computer involved placing a piece of paper over an expensive digitizing pad and using a special pen that produced digital data by indicating the coordinates of the digitizing pad. Thus, heretofore, there was no economic, convenient way for wirelessly entering information written on plain paper into a computer.
Another method utilized by the prior art for entering information into a computer involved the use of radio frequency identification (RFID) tags. The RFID tags were programmed to contain digital information either during the manufacturing of the read only memory portion of the RFID integrated circuit, or in the field using electromagnetic radio frequency signals to store information in the nonvolatile memory portion of the RFID tag. One of the difficulties involved in the utilization of RFID tags was that if an end user wanted to enter information into the RFID tag, the end user had to use a specialized device that communicated with the RFID tag through a radio frequency. Another problem involved in the utilization of RFID tags that were programmed by the manufacturer was that the end user had to share the information that was going to be programmed into the RFID tag with the manufacturer of the tag.
Bar codes have been used in a wide variety of applications as a source for information. Typically, bar codes are used at a point-of-sale terminal in merchandising for pricing and inventory control. Bar codes are also used in controlling personnel access systems, mailing systems, and in manufacturing for work-in-process and inventory control systems, etc. The bar codes themselves represent alphanumeric characters by series of adjacent stripes of various widths or lengths, i.e., the Universal Product Code, Planet Code, etc.
A bar code is a set of binary numbers. It consists of black bars and white spaces. A wide black bar space signifies a one, and a thin black bar or space signifies a zero. The binary numbers stand for decimal numbers or letters. There are several different kinds of bar codes. In each one, a number, letter or other character is formed by a certain number of bars and spaces.
Bar code reading systems or scanners have been developed to read bar codes. The bar code may be read by having a light beam translated across the bar code and a portion of the light illuminating the bar code is reflected and collected by a scanner. The intensity of the reflected light is proportional to the reflectance of the area illuminated by the light beam. This light is converted into an electric current signal, and then the signal is decoded.
Conventional bar codes are limited in the amount of information they contain. Even two-dimensional bar codes, such as PDF-417 and Code -1, are limited to a few thousand bytes of information for practical uses. The ability to encode greater information density is limited by the resolution of available scanning and printing devices.
It is also difficult to create or change a bar code without using a printing device.